Most fence and rail materials are either traditional lumber or thermoplastics. Typical plastics in these applications are PVC (polyvinyl chloride) and polyethylene. PVC typically does not have the strength and rigidity of wood and lumber and therefore, the rail for the fence and railing needs the steel or aluminum reinforcement channel inside the rail. These metal reinforcements are prone to corrosion attack, and lose strength in long-term endurance. Also, the problem exists as to the dark color of thermoplastic products. The dark color fence and rail made out of PVC or other polymeric materials has not been successful in the past. The products show bowing due to differences in expansion and contraction between the two different sides of the product upon exposure of sunlight. In addition, the dark color absorbs heat readily and the resultant uneven heat buildup causes this deformation. An additional problem is the lack of long-term stiffness of the products. It has limited the rail span between the posts to less than traditional lumber.
Thus, synthetic decks, whether composed of plastic or wood-plastic composite materials, do not fully satisfy market needs.
Wood-plastic composite planks are produced by extrusion, and the extrusion has various limitations. Extrusion uses an embossing roll to create a wood grain surface. The quality of such wood grains is often not particularly high. Furthermore, the wood composite deck planks are heavy, since the wood composite has a lower modulus and flexural strength, needing a thick wall to compensate for these strength levels. In addition, the wood composite deck does not have color fastness; it changes color from natural or gray to silver-gray over time, in a non-uniform manner when exposed to the outdoor environment.
As noted above, there is another class of synthetic deck planks available, namely the PVC profile decks. Such decks are produced by profile extrusion. In this type of production, it is often difficult to use an embossing roll to create the wood grain texture in a uniform nature on the deck surface. The pressure imposed by the embossing roll often cannot provide a uniform force, because the surface of a hollow and three-dimensional panel responds in a non-uniform manner to the particular force. As result, a “real wood” grain emulated surface is particularly difficult to achieve. The PVC profile deck also has a significant thermal expansion coefficient; installation requires care in order to accommodate the expansion and contraction of changes in temperature. In this regard, the dark color deck panel materials have not been practical, since the heat build-up on the surface is more pronounced for darker colored panels. Regarding color fastness, the darker color PVC is superior to wood-plastic composites, but still has the tendency to lose its original color to a visible degree. Furthermore, PVC has a tendency to become brittle with aging upon outdoor exposure, resulting in a loss of its impact strength.
The present invention serves to correct the shortcomings noted above. The deck panel produced in accordance with the present invention has superior resistance to color fading, possesses superior cold impact strength, has a well-defined wood grain surface, and is light-weight.
One of the objectives of the present invention is the production of a high strength plastic alternative to the traditional wrought iron or aluminum ornamental rail and fence. Metal fences and rails are constantly under the threat of corrosion attack, and need periodic painting. To date, there have not been any non-composite products with the necessary performance properties and aesthetic appearance comparable to these metal products. In that sense, there have not been any thermoplastic composite products in the market. The present invention discloses thermoplastic composite products that resemble wrought iron, and aluminum wrought iron alternative, but are maintenance-free, kink-free, light and perform equally as well.
An additional objective is to make the dark color thermoplastic post and rail fence (e.g., split post and rails) possible. The fiberglass reinforcement stabilizes the uneven contraction and expansion, in spite of different heat buildup on the surface.
A further objective of the present invention is providing non-metallic heavy duty rail and fence systems for use in industrial and commercial applications. The metallic railing in an industrial atmosphere is often exposed to chemical gases or acids and is prone to corrosion attack. The integrity of the industrial railing is critical for the safety of those in the workplace. The thermoplastic railing system that is strengthened by reinforcing tapes or rods of fiberglass/thermoplastic polymer composite provides superior strength and rigidity to its metal counterparts.